(CNN) – Beset by a sinking approval rating and an ongoing budget crisis, Massachusetts Gov. Deval Patrick is facing a gubernatorial challenge from a former member of his own party.

State Treasurer Timothy Cahill announced Wednesday he will formally challenge the one-term governor as an independent candidate next year, a move that could set up a civil-war of sorts in the state's Democratic Party.

"I do not enter this race to run against any individual or party," Cahill said in an official announcement speech in Boston. "Instead I run because I believe we need new leadership to make Massachusetts a vibrant place once again."

Patrick, a Harvard-educated lawyer and former member of the Clinton Justice Department, was elected overwhelmingly in 2006 but has since seen his poll numbers sputter after a series of controversies and the ongoing decline of his state's economy.

A Boston Globe survey earlier this summer put Patrick's approval rating at 35 percent, the lowest in his three-year tenure.

Cahill, who has served as the state's treasurer since 2003, formally severed ties with the Democratic Party earlier this summer, citing then his opposition to one party rule in the state and the Patrick administration's fiscal policy.

On the Republican side, former Harvard Pilgrim Health Care executive Charles Baker has announced he will also mount a gubernatorial run.